78 lines
2.1 KiB
GLSL
78 lines
2.1 KiB
GLSL
#version 100
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precision mediump float;
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uniform float u_time;
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uniform vec2 u_resolution;
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uniform vec2 u_mouse;
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uniform sampler2D u_backbuffer;
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// Gray-Scott parameters
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// standard "spots" / coral
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#define DA 1.0
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#define DB 0.5
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#define FEED 0.055
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#define KILL 0.062
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#define DT 1.0
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void main() {
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vec2 pixel = 1.0 / u_resolution;
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vec2 uv = gl_FragCoord.xy / u_resolution;
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// Read current state
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vec4 state = texture2D(u_backbuffer, uv);
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float a = state.r;
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float b = state.g;
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// Laplaclan (convolution)
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// 0.05 0.2 0.05
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// 0.2 -1 0.2
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// 0.05 0.2 0.05
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vec4 sum = vec4(0.0);
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sum += texture2D(u_backbuffer, uv + vec2(-1.0, -1.0) * pixel) * 0.05;
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sum += texture2D(u_backbuffer, uv + vec2( 0.0, -1.0) * pixel) * 0.2;
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sum += texture2D(u_backbuffer, uv + vec2( 1.0, -1.0) * pixel) * 0.05;
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sum += texture2D(u_backbuffer, uv + vec2(-1.0, 0.0) * pixel) * 0.2;
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sum -= state * 1.0;
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sum += texture2D(u_backbuffer, uv + vec2( 1.0, 0.0) * pixel) * 0.2;
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sum += texture2D(u_backbuffer, uv + vec2(-1.0, 1.0) * pixel) * 0.05;
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sum += texture2D(u_backbuffer, uv + vec2( 0.0, 1.0) * pixel) * 0.2;
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sum += texture2D(u_backbuffer, uv + vec2( 1.0, 1.0) * pixel) * 0.05;
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// Reaction-Diffusion logic
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// A' = A + (Da * lapA - A*B*B + f*(1-A)) * dt
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// B' = B + (Db * lapB + A*B*B - (k+f)*B) * dt
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float lapA = sum.r;
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float lapB = sum.g;
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float abb = a * b * b;
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float nA = a + (DA * lapA - abb + FEED * (1.0 - a)) * DT;
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float nB = b + (DB * lapB + abb - (KILL + FEED) * b) * DT;
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// Clamp
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nA = clamp(nA, 0.0, 1.0);
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nB = clamp(nB, 0.0, 1.0);
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// Mouse Interaction (Add B)
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float dist = distance(gl_FragCoord.xy, u_mouse);
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if (dist < 20.0 && u_mouse.x > 0.0) {
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nB = 0.9;
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}
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// Initialization (random noise at start)
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if (u_time < 0.5) {
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if (fract(sin(dot(uv, vec2(12.9898, 78.233))) * 43758.5453) > 0.99) {
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nB = 1.0;
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} else {
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nB = 0.0;
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nA = 1.0;
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}
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}
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gl_FragColor = vec4(nA, nB, 0.0, 1.0);
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}
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